A vehicle suspension arm is known which includes (a) an arm body having a longitudinal shape, (b) a wheel-side attachment portion that is disposed at one end of the arm body and coupled to the upper part of an axle carrier, and (c) a vehicle body-side attachment portion that is disposed at the other end of the arm body and coupled to a vehicle body. Patent Document 1 describes a technique of strengthening a curved portion of an arm body by heat treatment etc.